Colt/Auto-Ordnance Model 1921 AC Thompson Submachine Gun. Colt manufactured 15,000 Thompson Submachine Guns for the Auto-Ordnance Corporation in 1921. The original Model 1921 design featured a finned barrel with no compensator, pistol grip forearm, and had a rate of fire of approximately 800 rounds per minute. All of the Colt Thompsons had the Colt high polish commercial blue finish, were fitted with Lyman folding adjustable leaf sights and had straight grain, oil-finished, American walnut stocks, pistol grips and forearms. In 1926, Auto-Ordnance fitted a Cutts compensator to the Model 1921 Thompson Submachine Guns and designated the modified guns Model 1921 AC. The Model 1921 AC had the same internal components and external markings as the Model 1921 and retained the 800 round per minute rate of fire. This gun has the early, small, and unmarked Cutts compensator fitted to most Model 1921 AC Thompsons. The gun has the early style 1921 blued actuator with bronze Blish lock and bright finished bolt. The bolt and Blish lock correctly have no sub-contractor markings. The gun also has the early 1921 two-piece buffer and buffer pilot with large diameter recoil spring. The gun has all the original Colt/AO components with bright internal components in the frame and bright stock latch. The ejector, magazine latch, safety and fire control lever are all original Model 1921 Colt/AO components. The front of the stock is stamped with the tiny anchor mark that denotes the Remington Arms made stock used on the original Colt/AC Thompsons. The left side of the receiver is roll-stamped "MODEL OF 1921./NO 3259" in two lines. "THOMPSON SUBMACHINE GUN,/CALIBRE .45 AUTOMATIC COLT CARTRIDGE/MANUFACTURED BY/COLT PATENT FIRE ARMS MFG.CO/HARTFORD, CONN.,U.S.A." is roll-stamped in five lines on the left side of the receiver below the rear sight. The right side of the receiver is roll-stamped: "AUTO-ORDNANCE CORPORATION,/NEW YORK. U.S.A." in two lines below the rear sight followed by nine patent dates in five lines and the encircled "JHB" monogram of Auto-Ordnance inspector John H. Barrett found on many Colt/AO Model 1921 and Model 1928 submachine guns. The Auto-Ordnance bullet trademark is roll-stamped on the top of the receiver ahead of the rear sight. The rear sight base is marked: "MADE BY "LYMAN", MIDDLEFIELD. CONN, U.S.A." The left side of the frame has the second style "FIRE - SAFE" markings connected by and arrow with "FULL/AUTO" roll-stamped ahead of the fire selector in two lines and "SINGLE" below an arrow stamped behind it. The bottom of the frame is roll-stamped: "NO. 3259". The frame and receiver numbers match. Also included with the gun are: (1) an early Auto-Ordnance 50-round "L" drum magazine with Auto-Ordnance markings on the drum body and cover and 1920 patent dates on the body, (2) two early blued, 20-round magazines marked "PATENTED - AUG.24,1920/AUG.24, 1920-JAN.11, 1921" in two lines on the front of the magazine, and (3) nickel-plated oiler.